Diabetic Retinopathy
Overview This presentation covers the following topics: Definitions Epidemiology of diabetic retinopathy Evidence for public health approaches Screening for diabetic retinopathy Health education. Notes section a more detailed explanation is provided in the notes along with key references. 2
WHO definition DM (2006) Chronic disease, which occurs when the pancreas does not produce enough insulin, or when the body cannot effectively use the insulin it produces. Primarily defined by the level of hyperglycaemia giving rise to risk of microvascular damage (retinopathy, nephropathy, and neuropathy). Diagnostic criteria: fasting plasma glucose 7.0 mmol/l (126mg/dL) or 2 h plasma glucose 11.1 mmol/l (200mg/dL.
Magnitude of Diabetes Mellitus Globally 2005 > than 170 million DM patients Global estimates 2010: 285 million DM patients Global estimates 2030: 366 to 439 million DM patients.
Trends in DM epidemiology Why the increase? Population growth Population aging Urbanization Lifestyle change Obesity MJC2 1 Trend Most rapid changes in low and middle income countries DM and blindness: After 15 years of DM estimated: 2% become blind 10% develop severe visual impairment. 6
Slide 6 MJC2 I might suggest longer lifespans for diabetics because it is duration of diabetes that is key here Marissa Carter, 6/2/2011 1 This slide is epi for DM, I think you are refering to DR epi in the comment Covadonga Bascaran, 7/11/2011
Definition and classification of DR Characteristic group of lesions found in the retina of individuals that have had diabetes for several years. It is considered to be the result of vascular changes in the retinal circulation: a microangiopathy that exhibits features of both microvascular occlusion and leakage.
I1 2 Iernational classification R0 None No retinopathy R1 Mild Microaneurysms only R2 Moderate More than microaneurysms but not severe R3 Severe More then 20 haemorrhages Venous beading IRMA R4 Proliferative New vessels Vitreous haemorrhage M0 No maculopathy No macular oedema M1 Mild maculopathy Exudate / oedema away from fovea M2 Moderate maculopathy Exudate / oedema close to fovea M3 Severe maculopathy Exudates / oedema at fovea
Slide 8 I1 discuss this slide. ICRUDPAT, 3/22/2011 2 Covadonga Bascaran, 7/11/2011
Prevalence DR USA (WESDR) Prevalence of DR of any severity in the diabetic population as a whole is approximately 30%. Prevalence DR with risk of visual impairment is approximately 10%. Duration Prevalence Type 1 IDDM <5 yrs 13% 10 15 yrs 90% Type 2 IDDM <5 yrs 40% 15 20 yrs 84% MJC4 Type 2 NIDDM <5 yrs 24% 15 20 yrs 53%
Slide 9 MJC4 I find the prevalence data interesting for type 2 between IDDM and NIDDM groups; is that a general finding for other studies? Marissa Carter, 6/2/2011
What do we know about the epidemiology of DR Mainly based on population based studies from developed countries. Difficulties in comparing data due to varied study methodologies: Population based/hospital based or varied by DM type Varied age of inclusion, duration/onset of DM Sample size Definitions and classification. 10
Examples of DR prevalence surveys Country Prevalence Sample Age (%) USA WESDR (1) 996 1370 <30 >30 19.0 28.8 USA LALES (2) 1217 >40 46.9 India Chennai CURES (3) 1382 >20 17.6 UK Liverpool 395 15 92 33.0 Barbados (5) 636 >40 28.5 Australia Blue Mountains (6) China Beijing (7) 255 >50 32.0 235 >40 37% 11
Diabetic retinopathy and blindness Leading cause of blindness in working age population Globally estimated prevalence of blindness due to DR 5% (1.8 million persons) in 2002: 0% ( unknown) Africa 3 7% South East Asia and Western Pacific 15 17% Europe, USA Europe
Risk factors for DR Risk factor Duration Poor glycaemic control Hypertension Pregnancy Puberty Renal disease Modifiable/non modifiable No YES YES MJC5 PARTLY YES NO PARTLY YES Hyperlipidaemia YES 13
Slide 13 MJC5 I agree but there is a risk of increased hypoglycemic epidoes and death if control is too tight Marissa Carter, 6/2/2011
WESDR: Cumulative 10-yr Incidence VISUAL IMPAIRMENT 9.4% in young IDDM 37.2% in older IDDM 23.9% in older NIDDM BLINDNESS 1.8 % young IDDM 4.0 % older IDDM 4.8 % older NIDDM Factors influencing incidence: Baseline retinopathy at diagnosis Glycaemic management insulin Poor DM control high HbA1c Duration 14
Management of DR Laser first line treatment for DR Vitrectomy Experimental treatments Anti VEGF Intra vitreal steroid
Management of DR Stage of Disease Management options No DR or moderate non-proliferative DR Severe non-proliferative DR Proliferative DR High risk PDR not amenable to laser treatment CSME (clinically significant macular edema) Optimize medical glycaemic control, blood pressure and lipid s Consider scatter (pan-retinal ) laser photocoagulation. Better visual prognosis Immediate pan-retinal photocoagulation Additional vitrectomy for high-risk cases Vitrectomy Focal and or pan-retinal photocoagulation 16
Evidence for treatment of DR Trial Diabetic Retinopathy Study (DRS) Early Treatment Diabetic Retinopathy Study (ETDRS) Evidence PRP reduces the risk of severe visual loss by > 50 % in high risk proliferative diabetic retinopathy 1.Focal photocoagulation treatment for macular oedema. 2. No scatter treatment for eyes with mild to moderate NPDR, unless high risk. 3. Early vitrectomy for advanced active PDR. 4. Careful follow up for all DR patients. 5. No ocular contraindications for aspirin Diabetic Retinopathy Vitrectomy Study (DRVS) 1.Early vitrectomy in eyes with recent severe vitreous hemorrhage especially if IDDM. 2. Early vitrectomy in very severe PDR
Evidence for prevention Trial United Kingdom Prospective Diabetes Study (UKPDS) Diabetes Control and Complications Trial (DCCT) Evidence Lowering elevated blood glucose and BP levels significantly reduces lifethreatening complications of type 2 diabetes Intensive treatment reduces risk of ocular disease (76%), renal disease, and neuropathy
Public health approach to prevent visual loss due to DM Primary (to stop the DR from occurring) Health education, dietary/lifestyle changes Early diagnosis of diabetes Control of hyperglycaemia, hypertension, and dyslipidemia Secondary (to prevent blindness from occurring) Controlling hyperglycemia, hypertension, and dyslipidemia MJC6 3 Screening to detect treatable retinopathy Provision of laser photocoagulation Tertiary (to treat the blinding disease) Vitreo retinal surgery Rehabilitation of VI and blind
Slide 19 MJC6 Annual screening or merely unspecified periodic screening because of CE controversis over frequency? Marissa Carter, 6/2/2011 3 Discussed in later slide in detail Covadonga Bascaran, 7/11/2011
Screening Screening aims to answer simple question: Refer/do not refer for treatment. Screening is a public health service, for members of a defined population, they may not necessarily perceive they are at risk of, or are already affected by a disease or its complications, are offered a test, to identify individuals who are most likely to benefit from further tests or treatment to reduce the risk of a disease or its complications
Required criteria for screening Criteria Well defined, public health problem Known prevalence Known natural history Simple and safe test available Cost effective Acceptability by patients and professionals Agreed policy on treatment MJC7 Diabetic Retinopathy YES YES YES YES YES YES YES 21
Slide 21 MJC7 Problem is that a lot of patients don't care Marissa Carter, 6/2/2011
Components of a screening programme Identification of diabetic patients Call/Recall mechanism Screening method Grading Referral network Treatment and follow up pathway Information system Quality assurance
Sensitivity and specifity Sensitivity: the fraction of those with the disease correctly identified as positive by the test. Specificity: the fraction of those without the disease correctly identified as negative by the test. A DR screening program test must achieve 80% sensitivity and 95% specificity. (1) A high coverage is essential for an effective screening programme. 23 MJC8 4
Slide 23 MJC8 How do we define "high"? >= 80% Marissa Carter, 6/2/2011 4 UK programme aims for a minimun of 80%, with the objective to increase coverage anually. Covadonga Bascaran, 7/11/2011
Screening options Ophthalmoscopy by trained health personnel - Lower sensitivity. - May be the cheaper option in the initial stages Retinal photography - Higher sensitivity - Expensive - Permanent visual record if digital - Any ungradeable photos will need clinical examination using ophthalmoscopy.
Screening Personnel Professional Ophthalmoscopy Retinal photographs Sensitivity Specificity Sensitivity Specificity GP 25 66% 75 98% 87% 85% Optometrists 48 82% 94% 97% 87% Ophthalmol. Diabetologist 43 79% 89 100% 96% 98% 27 73% 98% 89% 92%
Intervals for screening Regular and timely to prevent blindness. Cost effective: systematic screening is expensive. Acceptability : especially as patients are asymptomatic Long intervals may reduce coverage. Liverpool diabetic eye study: No DR no risk factors 3 years. No DR insulin use >20 yrs 1 year Mild pre proliferate 4 months Longer intervals for patients who are low risk ( 70 %) = cost savings
Trade off between performance and cost Local decisions need to be made based on: Available infrastructure Available resources Social models for service delivery Models of screening technique, will need to be country specific. Standardised definitions and performance measures allow for comparable measures and maintaining quality. 27
Models of screening Static : Based at a health/optometry center/gp practice. Must be linked to an image grading center Mobile screening: An equipped van travels in a catchment area. Also linked to image grading center. Pathways: All photo images go to reading center for grading. Grading and advice for referral is communicated to patient. Ungradeable images patients see an ophthalmologist. Quality checks done by ophthalmologist. 28
Cost effectiveness of screening for DR Screening is cost effective than opportunistic examinations. Screening annually versus every 3 years and 5 years has shown to be marginally beneficially. Greatest benefit for annual screening is for younger, poorly controlled diabetics. Most modeling done to date is based on populations on high income countries.
Acceptance and barriers of screening for DR Compliance challenges: Asymptomatic condition Longer screening periods in lower risk cases : might lead to poorer compliance wrong message: visual loss not my problem Multiple health problems and health appointments. Barriers: Lack of awareness about DR as cause of blindness Fear of laser Inconvenience No family/employers support Guilt about glycaemic control Retinal images good impact for health education
Health education for DR Diabetic patients should receive adequate information regarding glycaemic control, diet and exercise Lack of persistent behavioural change in patients despite health education remains a challenge Marketing approach about the regular consultations and treatment is essential Orient educational messages to each culture 31
Conclusions on public health for DR DR is the leading cause of blindness in the working population and the trend is for it to increase. There are evidence based strategies for the DR management and prevention of blindness. Screening for DR is a cost effective tool for prevention of visual loss due to DR. Screening models need to be tailored for local resources. Health education and addressing patient barriers are essential to increase compliance 32 with screening and treatment.